The invention relates to a metal laminate gasket with a bore ring and engaging members thereof, to be disposed between a cylinder head and a cylinder block.
A metal laminate gasket having a bore ring around a hole to be sealed has been known and widely used. In this case, the bore ring is generally disposed inside a hole of a metal plate, and the bore ring and the metal plate are laminated with one or more metal plates to form the metal laminate gasket.
However, in the above metal gasket, in case the outer shape of the bore ring is formed symmetrically in some degree, when the bore ring is assembled with the metal plate, the bore ring may be assembled in a wrong assembly direction or upside down by mistake. In this case, once the bore ring is assembled incorrectly, it is difficult to confirm that the bore ring is assembled correctly or not.
In the metal laminate gasket, the assembly order of the metal plates of the gasket can be identified and checked by forming projections or holes to be aligned in a specific order, as disclosed in U.S. Pat. No. 5,141,237. Also, in a metal laminate gasket with a bore ring, the bore ring may have large width portions symmetrically arranged, which are located in depressions of a metal plate, such as disclosed in U.S. Pat. No. 5,957,463. Further, as means for identifying the thickness of a bore ring, the bore ring may have a projection with signs for identifying the thickness thereof, which is located in a specific position of the gasket, as disclosed in Japanese Patent Publication (KOKAI) No. 2000-220746.
However, there is no gasket having means for locating a bore ring in a specific position, which can be also checked after assembly.
Accordingly, one object of the invention is to provide a metal laminate gasket having a metal plate and a bore ring retained inside the metal plate, wherein the assembly direction of the bore ring with respect to the metal plate can be positioned easily without mistake.
Another object of the invention is to provide a metal laminate gasket as stated above, wherein the wrong assembly and non-assembly of the bore ring can be confirmed after assembly by utilizing the positioning structure of the bore ring to the metal plate.
Further objects and advantages of the invention will be apparent from the following description of the invention.
A metal laminate gasket of the invention is used for an internal combustion engine having a hole to be sealed. The gasket comprises a first metal plate extending substantially throughout an entire area to be sealed and having a first hole corresponding to the hole of the engine, a bore ring disposed under the first metal plate, and a second metal plate disposed under the first metal plate.
The bore ring has a second hole corresponding to the first hole and at least two first engaging members formed around an outer periphery thereof with a predetermined distance away from each other. The second metal plate includes a third hole having a size for receiving the outer periphery of the bore ring, and at least two second engaging members formed around an inner periphery thereof to engage the at least two first engaging member. The first and second engaging members are arranged such that the bore ring can be positioned and retained in the second metal plate in only one position even if the bore ring is positioned upside down.
The first engaging member is one of a projection and a dent, and the second engaging member is the other of the projection and the dent. The projection and dent may be made small to engage with each other.
The first metal plate may include an opening at a position where one set of the first and second engaging members are disposed, so that an engagement of the one set of the first and second engaging members is seen through the opening. Since the engagement of the first and second engaging members can be seen through the opening, the wrong assembly or non-assembly of the bore ring can be confirmed after assembly by utilizing the positioning structure of the bore ring to the metal plate.
The bore ring except for the at least two first engaging member may have a substantially non-circular shape. On the other hand, the bore ring except for the at least two first engaging members may have a symmetrical shape with respect to a predetermined plane. In any situations, the first and second engaging members are formed at non-symmetrical positions.